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Zhengzhou Huachen Instrument Co., Ltd
Working principle and core characteristics of vacuum freeze dryer
Date: 2025-05-15Read: 7
1、 Working principle
1. Preprocessing and Freezing
After pre-treatment such as cleaning and cutting, the material is rapidly cooled to below -30 ℃, causing the moisture to freeze into solid ice crystals and form a fixed microstructure. This process needs to be achieved through a quick freezing warehouse to ensure even distribution of ice crystals and avoid liquid water residue damaging the material form.
2. Vacuum sublimation dehydration
The frozen material is transferred to a vacuum drying chamber, where the vacuum system reduces the air pressure to below the triple point pressure of water (usually below 610.5 Pa), allowing ice crystals to sublime directly into water vapor and escape. At this stage, a small amount of thermal energy needs to be provided to maintain the energy required for sublimation, but the material temperature should always be below freezing point to avoid thermal damage.
3. Analysis drying (secondary drying)
After sublimation is completed, residual bound water is removed by heating to 10-30 ℃, further reducing the moisture content to 1% -4% to ensure long-term stable storage of the material. At this stage, it is necessary to strictly control the vacuum degree and temperature to prevent material structure collapse.
2、 Core Features
1. Low temperature activity retention
The operating temperature throughout the process should be below freezing point or slightly above room temperature (not exceeding 40 ℃) to avoid denaturation or degradation of heat sensitive substances (such as proteins and vitamins), and to preserve nutritional components and biological activity to a greater extent.
2. Porous structure and morphological stability
After the sublimation of ice crystals, a sponge like porous structure is formed, and the material volume remains almost unchanged. The rehydration rate is fast and the original properties can be restored. Compared to traditional drying methods, there are no issues such as shrinkage or hardening.
3. Wide applicability and high compatibility
It can handle various forms of materials such as liquids, solids, powders, etc., suitable for fields such as medicine, food, and biological products, especially for high-value or products with strict activity requirements.
4. Vacuum environment oxidation prevention
Drying under vacuum conditions, isolating oxygen, reducing the risk of material oxidation and deterioration, and extending shelf life.
5. Integration and automation control
The equipment integrates refrigeration, vacuum, heating, and dehumidification systems, and monitors temperature and pressure parameters in real-time through sensors to ensure precise and stable processes.
6. High energy consumption and cost
Long term maintenance of low-temperature vacuum environment is required, and the energy consumption of equipment operation is significantly higher than that of conventional drying technology, with a longer processing cycle.
The vacuum freeze dryer achieves efficient dehydration through low-temperature physical phase transition, becoming a technology for drying high activity and high value-added materials.
